Apparatus for smoothing coatings



March 1965 R. A. LABOMBARDE APPARATUS FOR SMOOTHING COATINGS 2 Sheets-Sheet 1 Filed Oct. 16, 1961 INVENTOR.

ros' arch 23, 1965 R. A. LABOMBARDE 3,174,875

APPARATUS FOR SMOOTHING commas 2 Sheets-Sheet 2 Filed Oct. 16. 1961 JNVENTOR.

EAYMQND A. LAB E 3,174,875 APPARATUS FGR SMOOTHHNG QOATHNGS Raymond A. Labornbarde, Lowell Road, Nashua, NJH. Filed Oct. 16, 1961, Ser. No. 145,217 11 Claims. (til. 118-1tl1) This invention relates to apparatus for producing a super smooth face on a plurality of coated, individual folded paper box blanks.

There have been many proposed devices for smoothing a coating on one face of a continuous Web of paper, the web being drawn through a smoothing zone while subjected to treatment. For example, in U.S. Patent 2,312,- 927 to Murray of March 2, 1943, a continuous web is drawn through a nip formed by a backup roll and a flexible, trailing blade, the blade being heated at its base. In U.S. Patent No. 2,381,942 to Wickwire of August 14, 1945, a continuous web is drawn over an unyieldable smoothing bar having a curved face, the bar being heated by gas flames. The handling and advancing of a continuous web does not present problems such as occur when it is attempted to advance a plurality of individual, often slippery, individual coated blanks through a smoothing zone.

In my co-pending application, Serial No. 113,517, filed May 29, 1-961, 1 have disclosed one solution to the problem wherein the smoothing apparatus is a pair of opposed flexible blades forming a nip and heated by the blanks themselves, the blanks being advanced through the nip by a pair of opposed knurled blank carrier rolls. In this application, the smoothing apparatus is a rigid, heavy, stationary smoothing bar which is heated from an external source and provided with a fiat, smooth face opposed by a blank advancing roll having a deformable surface, the path of the blanks being straight through the flattened nip of the apparatus. Thus despite the non-continuous, interrupted characteristics of an advancing stream of untimed box blanks, the box blanks are advanced past a stationary, heated, box iron type, smoothing bar without slippage and without bending of the blanks.

The principal object of this invention is, therefore, to provide-a flat, smooth face on a rigid, heated smoothing bar for the purpose of smoothing the coatings on a plurality of flat coated box blanks without adversely marking the coating or bending the blanks out of a flat plane.

Another object of the invention is to provide smoothing apparatus for producing a smooth face on thinly coated, cooled box blanks, the apparatus including a flat, smooth face on a heavy smoothing bar, or iron, heated above the melting point of the coating and a soft rubber surfaced, blank advancing roll for moving the individual blanks successively past the flat face of the bar.

A further object of the invention is to provide a hollow box iron type smoothing bar with a fiat, smooth blank-engaging face maintained at realtively high temperature by the circulation of hot oil through the bar and a power driven roll with a soft rubber surface forming a flattened, pressure nip with the bar, the roll advancing successive coated blanks through the nip for flatwise smoothing and remelting of the blank coatings ready for quenching or cooling into a high gloss.

Still another object of the invention is to provide smoothing apparatus for coated box blanks in which the blanks are advanced individually and successively along a horizontal, rectilinear path, by a yieldable, frictional engagement with their underfaces, past a heavy, spring mounted, stationary, heated, smoothing bar, having a flat, smooth face engaging the upper faces of the blanks, the bar melting and smoothing the blank coatings but not scuffing or removing any coating.

3,l7i,?5 Patented Mar. 23, 1965 Other objects and advantages of the invention will be apparent from the claims, the description of the drawings and from the drawings in which:

FIG. 1 is a front elevational view of the smoothing apparatus of the invention in use on a coating machine;

FIG. 2 is a plan view of the apparatus shown in FIG. 1;

FIG. 3 is a side elevational view of the apparatus shown in FIG. 1, and

FIG. 4- is an enlarged diagrammatic view similar to FIG. 3 showing the smoothing of a hot metal coating on a flat box blank as the blank is advanced through the nip formed by the flat, hard, smooth face of a heated, smoothing bar opposed by the flat, soft, rubber surface of a rotating carrier roll.

PEG. 5 is a diagrammatic view similar to FIG. 4 showing an endless, soft, rubber surfaced carrier belt having a straight stretch for pressing each blank against the flat, hard, smooth face of a heated smoothing bar.

Coating machines for applying hot melt coating compositions such as paraffin wax, microcrystalline wax or polyethylene, in various combinations, to box blanks are well known and, therefore, are not described in detail herein. As shown diagrammatically in FIGURE 4, such a machine 24) includes a coating zone 21 having one or more pairs 22 of upper coating rol s 23 and lower coating rolls 2-4 forming nips such as 25. A thin coating 27 of the hot melt coating composition 28 is applied to the upper face 29 of each successive flat box blank 3%) advanced horizontally along the paper line 32 by the nips of the rolls and a similar coating 33 is applied to the underface 34 of each blank. The thin coatings tend to cool and harden rapidly, because the blanks are usually at room temperature, so that little or no impregnation of coating into the body of the blank takes place. Preferably a set of driven blank carrier rolls 35 are provided, in this invention, to form a cooling zone 36 between the coating zone 21 and a smoothing, or glossing, zone 37, wherein the coatings 27 and 33 may be air dried to set and harden.

The individual blanks 30 are thus advanced successively into the smoothing zone 37 with the upper faces 29 presented unidirectionally upwardly and carrying a cooled, thin coating of hot melt coating composition 27. The coating 27 on each blank is, however, not glossy and mirror-like and includes various kinds of crows foot markings, nip marks and the like, whether applied in the manner shown or otherwise. The path of the blanks 30 is horizontal and rectilinear up to and including zone 37 but may angle downwardly at the end of zone 37 so that the leading edges 38 of each blank will enter between a pair of endless conveyors 41 and 42 in cooling apparatus 43 in cooling zone 44. The blanks are carried beneath the surface of a coolant liquid, such as water 45 in the apparatus 43, for final setting of the coatings which have been smoothed in zone 37, such cooling apparatus being conventional and well known in the trade.

The smoothing, or leveling, apparatus 50, in smoothing zone 37, includes a stationary, rigid, heavy smoothing bar 51, preferably of the box iron type, mounted transversely across the path of the blanks above paper line 32 and having a hard, fiat, smooth face 52 for engaging the thin coatings 27 on the upper faces 29 of each successive individual blank 36 The bar 51 includes the rearward face 53 inclined toward the approaching blanks and forming an acute interior angle with the blankcontacting face 52 and an obtuse, exterior angle, greater than with the plane of the blanks to form a sharp rearward edge 54 upon which the hot melt coating composition does not accumulate. Preferably, the bar 51 also includes the forward face 55 inclined toward the approaching blanks and forming an obtuse interior angle with the blank-contacting face 52 and an acute exterior angle, less than 90, with the plane of the blanks to constitute one side of a flared entrance mouth 56 at the nip 57 of the smoothing apparatus 50. Heating means 58 is provided preferably in the form of a hot oil circulating system 59 which continually supplies oil, at a temperature Well above the melting point of the composition 28, to the bar 51 for maintaining the blank contacting face 52 at sufiicient temperature to remelt and liquify the coating in its high speed passage past the bar 51.

Smoothing apparatus i) also includes a moving member, such as the roll 62, the portion 63 thereof oppositei face 52 continually advancing in the direction of the arrows and the roll extending transversely across the path of the blanks below paper line 32. The mounting of roll 62 is fixed and the mounting of bar 51 is spring loaded toward the roll but a gap, or predetermined, normal, clearance, exists between the portion 63 and the face 52 when there is no blank 30 therebetween. This is for the reason that the surface 64 of roll 62 is deformable, and soft and preferably of rubber with a durometer of about'SO and the surface 64- might be adversely affected if it touched the hot face 52 even tangentially. As shown in FIG. 4, when the leading edge 38 of each blank 30 is fed into the flared mouth 56, formed at the nip 57 by the face 55 of bar 51 and the curved face 64 of roll 62, the portion, or strip, 63 becomes flattened to an area substantially coextensive with the area of face 52. The roll 62 thus presses the coating 27 uniformly against the hot face 52 as the blank is advanced through the nip 5'7 by the frictional contact of surface 64 with the underface of the blank 34, or with the cooled coating 33 thereon. The heated, fiat face 52 remelts the exposed layer of the thin coating 27 to iron, smooth and level the layer into a mirrorlike, smooth finish with no crows-foot markings, longitudinal streaks, nip marks or bend marks. The deformable, resilient, yieldable surface 64 tends to flex upwardly into the spaces between successive blanks to knock off any accumulated coating on the leading or trailing edges of the blanks formed during the coating step and performs the same action on each side of the blanks as the blanks travel through the nip.

A preferred commercial embodiment of the invention is shown in FIGURES 1 to 3 wherein the smoothing apparatus 56' is mounted at the end 76 of the frame 71 of a roll coating machine 26. The blank advancing roll 62 isjournalled at each opposite end in suitable bearings '72 and 73 in the opposite side frame pieces 74 and 75 and is driven by the gear 76 connected to the gear train of the machine 20 to rotate in the direction of the arrows in synchronism wtih the other rolls of the machine. The

roll 62 carries the rubber sleeve 65 to form the soft, de-' formable surface 64 having a portion 63 proximate the paper line 32.

The stationary, heavy, rigid smoothing bar 51 is of generally cylindrical shape and hollow, with the hollow 86 connected in the hot oil system 5d, conventional with machine 2i), by suitable conduits 73 and 79 so that the bar 51 and face 52 are maintained at a temperature above the melting point of composition 28. .At blank speeds of 200 feet per minute, a width of about five-eighths inch for face 52 has been found to create a desirable high gloss on the blank coatings 27. The rearward inclined face 53 is preferably formed by grooving bar 51 longitudinally as at 77 and'a plurality of flat chordal faces 52 of different widths may be formed in the bar 51 as at 89 and 96 with grooves 81 and 82 corresponding to groove 77.

Each hollow, reduced end 83 or 84 of bar'51 is rotatable in a hole 35 or $6 through the enlarged base 87 or 88 of a pillow block member such as 91 or 92. Each pillow block member such as 87 is vertically slidable on a pair of posts 95 and 96 upstanding from a subframe piece 9'7 or 98 having slots 99 and 1% for adjustable connection by bolts 102 and 103 to a side framepieee '74 or 75 of frame 71. Coil springs 165 and 166 around the posts and 96 cause the bar 51 to be spring loaded downwardly toward roll 62. The upper portions 108 and 169 of members 91 and 92 are apertured at 110 and fill for a worm rod 112 meshed with gears 113 and 114 on vertical threaded shafts 115 and 116. Manual turning of rod 112 rotates the shafts 115 and 116 to move both ends of bar 51 upwardly or downwardly to vary the gap at the nip 57 in accordance with'the thickness of blanks 36 while still permitting the bar 51 to exert uniform downward pressure under influence of the coil springs 105 and 166.

A split clamp 118 is tightened on one end 84 of bar 51 by a suitable tightening bolt 120, the clamp 118 having an extension 121 extending in the same direction as a fixed element 122. A rod 123 is fixed at one end to element 122 and passes through an aperture 124 in extension 121, there being a knurled knob 125 threaded on the terminal end 126 of rod 123 whereby the bar 51 may be turned slightly on its longitudinal axis as desired. The flat face 52 is normally parallel to the paper line 32 but if desired may be slightly angled thereto by turning knob 125 to reduce the area of contact of face 52 with the coatings 27.

By moving the sub frame pieces 97 and 93, by means of slots @9 and ltit), the flat face 52 of bar 51 may be in advance of, exactly opposite, or in rear of the axis of roll 62. for producing areas of contract of desired widths or producing various degrees of nip pressure in the area of contact. The particular relationship shown in FIGURES l to 3 has been found to give the best results with a hot melt coating composition of 75% paraflin, 25% polyethylene, with a melting point of 180 F., the bar face 52 being at 220 F., and a blank speed of about 200 feet per minute.

The surface 64 of roll 62 is preferably formed by an endless member sleeved on the roll. However, as shown in FIG. 5, the deformable surface 164 may be in the form of an endless belt 130 trained around a pair of rolls 131 and E32, the belt and. rolls being toothed for positive drive. Sets of pressure rolls, or a suitable pressure plate 133, may be provided whereby the straight upper stretch 134 present uniform resistance to the pressure of the flat face 128 of the heating bar 129.

It is preferred that the flexible, resilient surface 64 or 164, whether sleeved on a single roll 62 or in the form of an endless belt, or blanket, 130, be cooled to prevent deterioration of the surface under heat and to secure a better grip on the waxed underface of the advancing blanks. The rolls 62 and the rolls 131 and 132 are, therefore, hollow and connected at'each opposite end to conduit Mil and 141 so that a pump 142 may continually circulate the coolant 45 through the rolls.

It is also preferred that the surface 64 of the soft, flexible, resilient, sleeve 65, or the surface 164 of the endless belt, or blanket, 136, be continually scraped clean of wax spots. A stationary doctor blade may be used but such a blade tends to unduly wear the soft surface 64 or 164-.

It has been found, however, that wearis negligible and results excellent when a hollow roll 145, having a smooth hard face 146 is reversely rotated in contact with surface 64 or 164 While heated by suitable connection 147 with the hot oil circulating system 59. A stationary doctor blade 148 is provided to scrape the wax from the face 146, which has'been picked up as a reverse roll coating on face 146 from the surface 64 or 164.

I claim: I V

1. Apparatus forsmoothing a thin, cool coating of hot melt coating composition on one face of a plurality of boxblanks advancing individually and successively along a rectilinear path into the smoothing zone of a box blank treating machine, said apparatus comprising a stationary, rigid, heavy, smoothing bar mounted transversely across said path, said bar having a hard, fiat, smooth face extending at least one half inch along, and parallel to the plane of, said path, said face flatwise engaging the coatings on said blank; a blank advancing roll mounted transversely across said path opposite said bar, said roll having a soft rubber friction surface with a predetermined clearance from said bar face in the absence of a blank therebetween, but adapted to form a flattened nip with the flat smooth face of said bar, as each successive blank passes therebetween and to form a compressed, movable, flat area of contact on said roll surface parallel to, and coextensive in length with, said face of said bar; heating means on said apparatus continuously supplying heat to said bar for maintaining the temperature of said flat face above the melting point of said coating; pressure means on said apparatus continually urging said bar toward said roll with a predetermined pressure, permitting said bar face to resiliently yield and maintaining said bar face in parallelism with the plane of said blank path during said yielding to form said flattened nip and drive means on said apparatus for rotating said roll to advance said blanks through said nip and through said smoothing zone.

2. Apparatus as specified in claim 1 wherein said smoothing bar is of hollow, generally cylindrical shape with hollow ends of reduced diameter and said heating means comprises a hot oil circulating system having conduits connecting the same to each opposite end of said bar for including in said system the interior of said hollow ends and bar.

3. Apparatus as specified in claim 1 wherein said smoothing bar is a hollow cylinder, said flat face is chordal to the curved exterior face of said cylinder and the exterior face of said cylinder includes a longitudinal groove having an inclined face at an obtuse exterior angle, and an acute interior angle, to the plane of said flat face and with the plane of said blanks for forming a sharp longitudinal edge at the rearward terminus of said flat face at the exit of said nip.

4. Apparatus as specified in claim 1 wherein said smoothing bar includes a forward inclined face at the entrance of said nip, forming an obtuse, interior angle, and an acute exterior angle, with said fiat face and with the plane of said blanks (for avoiding scufling of the coating on said 'blanks and a forwardly inclined rearward face at the exit of said nip forming an acute interior angle, and an obtuse exterior angle, with the said flat face and with the plane of said blanks for avoiding accumulation of coating on said bar.

5. Apparatus as specified in claim 1 wherein the soft rubber friction surface of said roll is of substantial depth and said rubber has a durorneter of 50 to 60.

6. Apparatus as specified in claim 1 wherein said drive means rotates said roll at a surface speed of 200 feet per minute, the flat face of said bar is about five eighths inches in width and said heating means maintains said flat face at a temperature of about 220280 F.

7. Apparatus for smoothing a plurality of box blanks, each having a thin, cool coating of hot melt coating composition on the upper face thereof, said apparatus comprising means for advancing said blanks individually and successively along a horizontal, rectilinear path through a smoothing zone; a rigid, heavy, stationary, box iron mounted transveresly of, and above said path, said box iron having a flat, smooth, hard face extending at least one half inch along, and parallel to, the plane of said blank path, and engaging and smoothing the coating on each successive blank advancing through said zone; heating means connected to the hollow interior of said box iron for maintaining the temperature of said flat face at well above the melting point of said hot melt coating composition; a rotatable, blank-contacting roll having a soft, flexible, resilient deformable surface, said roll being mounted transversely of, and below said path opposite said box iron to revolve on a fixed axis to form a flattened nip having an area of blank contact parallel to, and co extensive in area with the flat face of said box iron when a blank passes therebetween; yieldable spring-load means,

associated with said box iron urging the same toward said roll at a predetermined pressure, the surface of said roll engaging the lower faces of each successive blank and uniformly pressing the upper faces thereof into contact with the hard, flat, smooth face of said box iron; drive means rotating said roll for advancing said blanks individually and successively through said flattened nip and means on said apparatus for maintaining a predetermined minimum clearance between the flat face of said bar and the surface of said roll in the absence of a blank therebetween.

8. Apparatus for glossing and smoothing a plurality of individual box blanks, each having a thin, cooled coating of hot melt coating composition on one face thereof, said apparatus comprising means for advancing said blanks individually and successively along a horizontal, rectilinear path with the coated faces thereof presented unidirectionally; rigid, stationary, smoothing bar means mounted along said path, said bar means having a flat, hard, smooth face extending in a plane parallel to the plane of said path for flatwise engaging the coated faces of said blanks, a forward face inclined toward said advancing blanks and forming an obtuse, interior angle with said flat face for preventing scufling of said coating and a rearward face inclined toward said advancing blanks and forming an acute interior angle with said flat face for preventing accumulation of said coating at the lower edge thereof, power driven roll means mounted along said path, opposite said bar means and forming a pressure nip with said flat, hard, smooth face when receiving said blanks and advancing the same further along said path, said roll means having a yieldable, resilient, soft blankcontacting surface normally spaced from, but adapted to flatten and press successive blanks against said smooth flat, hard face of said bar and means for heating said bar means for maintaining the temperature of the smooth, hard flat face thereof at about F. above the melting point of said hot melt coating composition.

9. In a coating machine having means for advancing a plurality of flat box blanks individually and successively along a rectilinear path, means mounted along said path for applying a thin, hot melt coating to at least one face of each successive advancing blank and means along said path for cooling the coatings on each successive advancing blank, the combination of smoothing mechanism, mounted along said path, in rear of said coating means and of said cooling means, said mechanism including a stationary, rigid, heavy smoothing bar having a flat, smooth, hard face extending at least one half inch in a plane parallel to the plane of said path for flatwise engaging the coatings on each successive blank; heating means maintaining the temperature of said face at Well above the melting point of said coating, a rearward face on said smoothing bar defining an acute interior angle with said blank engaging face; a rotatable, blank-engaging roll opposite said smoothing bar, said roll having a resilient, soft, deformable surface normally spaced from, but adapted to form a flattened area of blank contact parallel to, and coextensive in area with the hard, smooth, flat face of said bar and advancing each successive blank therebetween and drive means, synchronized with said blank advancing means, for rotating said roll to advance each successive blank through said nip while its coated face is remelted and smoothed into a high gloss by the fiat face of said bar.

10. Apparatus for producing a high gloss on a thin, cool coating of hot melt coating composition on one face of a plurality of flat box blanks advancing individually and successively along a rectilinear path into a smoothing zone of a box blank treating machine, said apparatus comprising a stationary, rigid, smoothing bar mounted transversely across said path in said smoothing zone, said bar having a hard, flat, smooth face extending in a plane parallel to the plane of said path and adapted to engage the said coatings on said blanks; heating means on said apparatus continuously supplying heat to the flat, smooth,

hard face of said bar for maintaining the temperature of said flat face at well above the melting point of said coating; an endless blank carrier mounted transversely across said path, opposite said bar, a portion of said carrier forming a nip with a predetermined clearance slightly less than the thickness of a blank with the flat, smooth face of said bar and being movable rectilinearly along said path; a soft, flexible, resilient surface on said carrier, said nip forming portion thereof being adapted to flatten into an area of blank contact parallel to, and coextensive in area with said flat face for frictionally gripping the face of each blank opposite to said coated face and resiliently pressing the coated face thereof against the smooth face of said bar and drive means, operably connected to said blank carrier and moving the flattened nip portion thereof along said path, for advancing said coated blanks along said path and through said nip with the coated faces thereof smoothed by said bar.

11. In a machine for coating a plurality of flat sheets advancing individually and successively along a horizontal, rectilinear path the combination of:

roll coating means mounted along said path depositing a layer of hot melt coating composition on the upper faces of each successive sheet advancing along said path; cooling means further along said path for cooling and hardening said coatings; a heated, smoother bar mounted further along said path, 7 said bar having a flat, hard, smooth face extending at least five eighths of an inch along, and parallel to said path under which the cooled, coated, upper faces of said sheets pass;

an endless conveyor means having a soft, resilient, friction, exterior surface over which said sheets pass, said surface and said flat face forming a nip therebetween with a predetermined normal clearance slightly less than the thickness of a sheet;

spring load means on said smoother bar urging said flat face toward said soft, resilient surface for flattening said surface into parallelism with said face as each successive sheet passes through said nip, and

means for maintaining continuous travel, along said path, of the surface of said conveyor forming said nip for frictionally advancing each successive sheet under, and in fiatwise smoothing engagement with said flat face.

References Cited by the Examiner UNITED STATES PATENTS RICHARD D, NEVIUS,-Primary Examiner. JOSEPH B. SPENCER, Examiner. 

9. IN A COATING MACHINE HAVING MEANS FOR ADVACING A PLURALITY OF FALT BOX BALNKS INDIVIDUALLY AND SUCCESSIVELY ALONG A RECTILINEAR PATH, MEANS MOUNTED ALONG SAID PATH FOR APPLYING A THIN, HOT MELT COATING TO AT LEAST ONE FACE OF EACH SUCCESSIVE ADVANCING BLANK AND MEANS ALONG SAID PATH FOR COOLING THE COATINGS ON EACH SUCCESSIVE ADVANCING BLANK, THE COMBINATION OF SMOOTHING MECHANISM, MOUNTED ALONG SAID PATH, IN REAR OF SID COATING MEANS AND OF SAID COOLING MEANS, SAID MECHANISM INCLUDING A STATIONARY, RIGID, HEAVY SMOOTHING BAR HAVING A FLAT, SMOOTH, HARD FACE EXTENDING AT LEAST ONE HALF INCH IN A PLANE PARALLEL TO THE PLANE OF SID PATH FOR FLATWISE ENGAGING THE COOLING ON EACH SUCCESSIVE BLANK; HEATING MEANS MAINTAINING THE TEMPERATURE OF SAID FACE AT WELL ABOVE THE MELTING POINT OF SAID COATING, A REAWARD FACE ON SAID SMOOTHING BAR DEFINING AN ACUTE INTERIOR ANGLE WITH SAID BLANK ENGAGING FACE; A ROTATABLE, BLANK-ENGAGING ROLL OPPOSITE SAID SMOOTHING BAR, SAID ROLL HAVING A RESILIENT, SOFT, DEFORMABLE SURFACE NORMALLY SPACED FROM, BUT ADAPTED TO FORM A FLATTENED AREA OF BLANK CONTACT PARALLEL TO, AND COEXTENSIVE IN AREA WITH THE HARD, SMOOTH, FLAT FACE OF SAID BAR AND ADVANCING EACH SUCCESSIVE BLANK THEREBETWEEN AND DRIVE MEANS, SYNCHRONIZED WITH SID BLANK ADVANCING MEANS, FOR ROTATING SAID ROLL TO ADVANCE EACH SUCCESSIVE BALNK THROUGH SAID NIP WHILE ITS COATED FACE IS REMELTED AND SMOOTHED INTO A HIGH GLOSS BY THE FALT FACE OF SAID BAR. 